Liquid crystal display device with spacer in the sealant

ABSTRACT

In a seal portion of a liquid crystal display device, column spacers are formed on a counter substrate side, organic passivation films are formed so as to face the column spacers on a TFT substrate side, and the gap between the TFT substrate and the counter substrate is controlled by the column spacers and the organic passivation films. A sealing material covers the column spacers and the organic passivation films and is in contact with an inorganic film formed on the TFT substrate on the TFT substrate side. Therefore, the adhesive force of the sealing material is improved to ensure the reliability of the seal portion.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese application JP2008-318313 filed on Dec. 15, 2008, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device and more particularlyto a liquid crystal display device excellent in reliability of a sealportion.

2. Description of the Related Art

The uses of liquid crystal display devices have been expanded intovarious fields because they can be made thin. In the liquid crystaldisplay device, a color filter substrate having color filters or thelike formed at places corresponding to pixel electrodes faces a TFTsubstrate having the pixel electrodes, thin film transistors (TFTs), orthe like formed in a matrix, and liquid crystal is interposed betweenthe TFT substrate and the color filter substrate. The transmittance oflight through liquid crystal molecules is controlled in each pixel, sothat an image is formed.

In the TFT substrate, data lines extending in the vertical direction andarranged in the lateral direction and scanning lines extending in thelateral direction and arranged in the vertical direction are present. Apixel is formed in a region surrounded by the data lines and thescanning lines. The pixel mainly includes the pixel electrode and thethin film transistor (TFT) as a switching element. A large number ofpixels formed in a matrix as described above form a display region.

The TFT substrate and a counter substrate are bonded together via asealing material formed at the peripheries of the substrates. In thedisplay region in this case, a gap between the TFT substrate and thecounter substrate is defined via column spacers formed on the countersubstrate to form a liquid crystal layer to a predetermined thickness.In a seal portion, glass fibers are mixed into the sealing material, sothat the thickness of the seal portion is defined by the diameter of theglass fiber.

However, when the way of determination for the gap between the TFTsubstrate and the counter substrate is different between the displayregion and the seal portion, the reliability of the seal portion isimpaired, or display unevenness occurs due to the non-uniformity of thegap. JP-A-2001-174827 describes the configuration which makes the gapuniform between the TFT substrate and the counter substrate by usingcolumn spacers also in the seal portion.

SUMMARY OF THE INVENTION

In the technique described in JP-A-2001-174827, although the columnspacers are formed also in the seal portion, there is no description orteaching about the reliability of the seal portion. In the configurationof JP-A-2001-174827, an alignment film is formed on the TFT substrate,and an alignment film is also formed on the column spacers in the sealportion formed on the counter substrate. The alignment film is anorganic material, so that there arises a problem of the adhesiveproperties between organic materials, resulting in a problem of thereliability of the seal portion.

Also in the technique described in JP-A-2001-174827, when the columnspacers are formed in the counter substrate, a black matrix is presentat the base of the column spacer both in the display region and in theseal portion. However, there is no description about the relationshipbetween the column spacer and the configuration on the TFT substrateside. The configuration on the TFT substrate side which the columnspacers face are very important in view of the relationship of the gapsin the display region and the seal portion as well as in view of thereliability of the seal portion.

It is an object of the invention to make the gap between the TFTsubstrate and the counter substrate constant in the display region andthe seal portion as well as to improve the reliability of the sealportion.

To attain the foregoing object, the invention employs specific means aswill be set forth below.

(1) A liquid crystal display device includes: a TFT substrate havingpixels each including a pixel electrode and a TFT formed in a matrix toform a display region; a counter substrate having color filters formedcorresponding to the pixels and facing the TFT substrate via a sealportion formed at the peripheries of the substrates; and liquid crystalinterposed between the TFT substrate and the counter substrate, whereinthe TFT is covered with an inorganic passivation film and an organicpassivation film, the gap between the TFT substrate and the countersubstrate is defined in the seal portion by column spacers formed on thecounter substrate and island-like organic passivation films formed onthe TFT substrate, and in the seal portion, a sealing material coversthe column spacers and the organic passivation films formed like islandsand is in contact with the inorganic passivation film on the TFTsubstrate side.

(2) The liquid crystal display device according to (1), wherein secondcolumn spacers are formed outside the portion where the sealing materialis formed on the counter substrate side, and second organic passivationfilms formed like islands are formed so as to face the second columnspacers on the TFT substrate side.

(3) The liquid crystal display device according to (1), wherein secondcolumn spacers are formed on the display region side of the portionwhere the sealing material is formed on the counter substrate side, andsecond organic passivation films formed like islands are formed so as toface the second column spacers on the TFT substrate side.

(4) A liquid crystal display device includes: a TFT substrate havingpixels each including a pixel electrode and a TFT formed in a matrix toform a display region; a counter substrate having color filters formedcorresponding to the pixels and facing the TFT substrate via a sealportion formed at the peripheries of the substrates; and liquid crystalinterposed between the TFT substrate and the counter substrate, whereinthe TFT is covered with an inorganic passivation film and an organicpassivation film, the gap between the TFT substrate and the countersubstrate is defined in the seal portion by column spacers formed on thecounter substrate and island-like organic passivation films formed onthe TFT substrate, in the seal portion, a sealing material covers thecolumn spacers and the organic passivation films formed like islands andis in contact with the inorganic passivation film on the TFT substrateside, and in the seal portion, semiconductor films are formed likeislands on the TFT substrate side.

(5) A liquid crystal display device includes: a TFT substrate havingpixels each including a pixel electrode and a TFT formed in a matrix toform a display region; a counter substrate having color filters formedcorresponding to the pixels and facing the TFT substrate via a sealportion formed at the peripheries of the substrates; and liquid crystalinterposed between the TFT substrate and the counter substrate, whereinthe TFT is covered with an inorganic passivation film and an organicpassivation film, the gap between the TFT substrate and the countersubstrate is defined in the seal portion by column spacers formed on thecounter substrate and island-like organic passivation films formed onthe TFT substrate, in the seal portion, a sealing material covers thecolumn spacers and the organic passivation films formed like islands andis in contact with the inorganic passivation film on the TFT substrateside, and in the seal portion, color filters are formed like islands onthe counter substrate side.

(6) A liquid crystal display device includes: a TFT substrate havingpixels each including a pixel electrode and a TFT formed in a matrix toform a display region; a counter substrate having color filters formedcorresponding to the pixels and facing the TFT substrate via a sealportion formed at the peripheries of the substrates; and liquid crystalinterposed between the TFT substrate and the counter substrate, whereinthe TFT is covered with an inorganic passivation film and an organicpassivation film, a counter electrode is formed on the organicpassivation film, an inter-layer insulating film is formed on thecounter electrode, the pixel electrode is formed on the inter-layerinsulating film, the gap between the TFT substrate and the countersubstrate is defined in the seal portion by column spacers formed on thecounter substrate and island-like organic passivation films formed onthe TFT substrate, and in the seal portion, a sealing material coversthe column spacers and the organic passivation films formed like islandsand is in contact with the inter-layer insulating film on the TFTsubstrate side.

(7) The liquid crystal display device according to (6), wherein in theseal portion, the column spacers formed on the counter substrate are incontact with the inter-layer insulating film formed on the island-likeorganic passivation films formed on the TFT substrate.

(8) A liquid crystal display device includes: a TFT substrate havingpixels each including a pixel electrode and a TFT formed in a matrix toform a display region; a counter substrate having color filters formedcorresponding to the pixels and facing the TFT substrate via a sealportion formed at the peripheries of the substrates; and liquid crystalinterposed between the TFT substrate and the counter substrate, whereinthe TFT is covered with an inorganic passivation film, in the sealportion, first scanning line lead wires and second scanning line leadwires are formed in different layers on the TFT substrate, the gapbetween the TFT substrate and the counter substrate is defined in theseal portion by column spacers formed on the counter substrate, and inthe seal portion, a sealing material covers the column spacers and is incontact with the inorganic passivation films on the TFT substrate side.

(9) A liquid crystal display device includes: a TFT substrate havingpixels each including a pixel electrode and a TFT formed in a matrix toform a display region; a counter substrate having color filters formedcorresponding to the pixels and facing the TFT substrate via a sealportion formed at the peripheries of the substrates; and liquid crystalinterposed between the TFT substrate and the counter substrate, whereinthe TFT is covered with an inorganic passivation film, a counterelectrode is formed on the inorganic passivation film, an inter-layerinsulating film is formed on the counter electrode, the pixel electrodeis formed on the inter-layer insulating film, in the seal portion, firstscanning line lead wires and second scanning line lead wires are formedin different layers on the TFT substrate, the gap between the TFTsubstrate and the counter substrate is defined in the seal portion bycolumn spacers formed on the counter substrate, and in the seal portion,a sealing material covers the column spacers and is in contact with theinter-layer insulating film on the TFT substrate side.

According to the invention, in the seal portion, the gap between the TFTsubstrate and the counter substrate is defined by the column spacersformed on the counter substrate and the island-like organic passivationfilms formed on the TFT substrate, similarly to the display region.Accordingly, since the gap between the TFT substrate and the countersubstrate is precisely set in the display region and the seal portion,particularly the reliability of the seal portion can be ensured.

Further, since the sealing material is in contact with the inorganicpassivation film or inter-layer insulating film formed of SiN on the TFTside, the adhesive force of the sealing material can be ensured, and thereliability of the seal portion can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a liquid crystal display device.

FIG. 2 is a cross-sectional view of a display region of a liquid crystaldisplay device of Embodiment 1.

FIG. 3A shows a first shape of a seal portion in Embodiment 1.

FIG. 3B shows the first shape of the seal portion in Embodiment 1.

FIG. 3C shows the first shape of the seal portion in Embodiment 1.

FIG. 4A shows a conventional example corresponding to FIG. 3A.

FIG. 4B shows the conventional example corresponding to FIG. 3B.

FIG. 4C shows the conventional example corresponding to FIG. 3C.

FIG. 5A shows a second shape of the seal portion in Embodiment 1.

FIG. 5B shows the second shape of the seal portion in Embodiment 1.

FIG. 5C shows the second shape of the seal portion in Embodiment 1.

FIG. 6A shows the conventional example corresponding to FIG. 5A.

FIG. 6B shows the conventional example corresponding to FIG. 5B.

FIG. 6C shows the conventional example corresponding to FIG. 5C.

FIG. 7A shows a third shape of the seal portion in Embodiment 1.

FIG. 7B shows the third shape of the seal portion in Embodiment 1.

FIG. 7C shows the third shape of the seal portion in Embodiment 1.

FIG. 8A shows the conventional example corresponding to FIG. 7A.

FIG. 8B shows the conventional example corresponding to FIG. 7B.

FIG. 8C shows the conventional example corresponding to FIG. 7C.

FIG. 9 shows a fourth shape of the seal portion in Embodiment 1.

FIG. 10A shows a first configuration in which a seal portion isroughened to improve adhesive force.

FIG. 10B shows the first configuration in which the seal portion isroughened to improve adhesive force.

FIG. 11A shows a second configuration in which a seal portion isroughened to improve adhesive force.

FIG. 11B shows the second configuration in which the seal portion isroughened to improve adhesive force.

FIG. 12A shows a third configuration in which a seal portion isroughened to improve adhesive force.

FIG. 12B shows the third configuration in which the seal portion isroughened to improve adhesive force.

FIG. 13A shows a fourth configuration in which a seal portion isroughened to improve adhesive force.

FIG. 13B shows the fourth configuration in which the seal portion isroughened to improve adhesive force.

FIG. 14A shows a fifth configuration in which a seal portion isroughened to improve adhesive force.

FIG. 14B shows the fifth configuration in which the seal portion isroughened to improve adhesive force.

FIG. 15A shows a sixth configuration in which a seal portion isroughened to improve adhesive force.

FIG. 15B shows the sixth configuration in which the seal portion isroughened to improve adhesive force.

FIG. 16 is a cross-sectional view of a display region of a liquidcrystal display device of Embodiment 2.

FIG. 17A shows a first shape of the seal portion in Embodiment 2.

FIG. 17B shows the first shape of the seal portion in Embodiment 2.

FIG. 17C shows the first shape of the seal portion in Embodiment 2.

FIG. 18A shows the conventional example corresponding to FIG. 17A.

FIG. 18B shows the conventional example corresponding to FIG. 17B.

FIG. 18C shows the conventional example corresponding to FIG. 17C.

FIG. 19A shows a second shape of the seal portion in Embodiment 2.

FIG. 19B shows the second shape of the seal portion in Embodiment 2.

FIG. 19C shows the second shape of the seal portion in Embodiment 2.

FIG. 20A shows the conventional example corresponding to FIG. 19A.

FIG. 20B shows the conventional example corresponding to FIG. 19B.

FIG. 20C shows the conventional example corresponding to FIG. 19C.

FIG. 21A shows a third shape of the seal portion in Embodiment 2.

FIG. 21B shows the third shape of the seal portion in Embodiment 2.

FIG. 21C shows the third shape of the seal portion in Embodiment 2.

FIG. 22A shows the conventional example corresponding to FIG. 21A.

FIG. 22B shows the conventional example corresponding to FIG. 21B.

FIG. 22C shows the conventional example corresponding to FIG. 21C.

FIG. 23 shows a fourth shape of the seal portion in Embodiment 2.

FIG. 24 shows a first shape of a seal portion in Embodiment 3.

FIG. 25 shows a second shape of the seal portion in Embodiment 3.

FIG. 26 shows a third shape of the seal portion in Embodiment 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The content of the invention will be disclosed in detail according toembodiments.

Embodiment 1

FIG. 1 is a plan view of a liquid crystal display panel according to theinvention. FIG. 1 shows a small liquid crystal display panel used for aDSC (Digital Still Camera) or the like. In the liquid crystal displaypanel, a TFT substrate 100 having pixels formed in a matrix and acounter substrate 200 having color filters formed thereon are bondedtogether via a sealing material 20 at the peripheries of the substrates.The TFT substrate 100 is formed larger than the counter substrate 200.On a portion of the TFT substrate 100 where the TFT substrate 100 islarger than the counter substrate, an IC driver 30 is arranged and aterminal portion is formed.

In FIG. 1, scanning lines extend in the lateral direction on the TFTsubstrate 100 and routed around to the terminal portion side viascanning line lead wires on both sides of the TFT substrate. Since aframe portion outside a display region has a small width, the scanningline lead wires are formed as two-layer wiring. The scanning line leadwires routed around to the terminal portion are connected to the ICdriver 30.

FIG. 2 is a cross-sectional view of the liquid crystal display panel inthe display region. FIG. 2 is a cross-sectional view showing theconfiguration of a most typical TN type liquid crystal display panel. InFIG. 2, a gate electrode 101 is formed on the TFT substrate 100. Thegate electrode 101 is formed by sputtering and thereafter patterned byphotolithography. The gate electrode 101 is formed of Al with athickness of about 300 nm. Not-shown scanning lines or the like aresimultaneously formed in the same layer as the gate electrode 101.Common wiring lines which are formed on the TFT substrate 100 forsupplying a common voltage to a counter electrode 204 of the countersubstrate 200 are also simultaneously formed in the same layer. A gateinsulating film 102 is formed so as to cover the gate electrode 101. Forexample, the gate insulating film 102 is formed by sputtering SiN film.The thickness of the gate insulating film 102 is about 400 nm, forexample.

A semiconductor layer 103 is formed above the gate electrode 101 via thegate insulating film 102. The semiconductor layer 103 is formed of a-Siwith a thickness of about 150 nm. A channel region of TFT is formed inthe a-Si layer. Before disposing a source electrode 105 and a drainelectrode 106 in the a-Si layer, an n+Si layer 104 is formed for formingan ohmic contact between the a-Si layer and the source electrode 105 orthe drain electrode 106.

The source electrode 105 or the drain electrode 106 is formed on then+Si layer 104. In the same layer as the source electrode 105 or thedrain electrode 106, a ground wire or the like which is connected withvideo signal lines, protective diodes, or the like is formed. The sourceelectrode 105 or the drain electrode 106 is formed of Mo, Al, or thelike. When Al is used, Al is covered with Mo or the like at the upperand lower surfaces thereof. This is because contact resistance sometimesbecomes unstable when Al is in contact with ITO or the like in a contacthole 113 portion.

After forming the source electrode 105 or the drain electrode 106,channel etching is performed using the source electrode 105 and thedrain electrode 106 as masks. For completely removing the n+Si layer 104from the channel layer, etching is performed up to the upper portion ofthe a-Si layer, so that a channel etching region 109 is formed.Thereafter, an inorganic passivation film 107 is formed so as to coverthe entire TFT. The inorganic passivation film 107 is formed of SiN. Thethickness of the inorganic passivation film 107 is about 400 nm, forexample.

An organic passivation film 108 is formed so as to cover the inorganicpassivation film 107. The organic passivation film 108 is formed thickbecause it functions as a planarization film. For example, the organicpassivation film 108 is formed to a thickness of about 2 μm. Forexample, an acrylic resin is used for the organic passivation film 108.A photosensitive acrylic resin is used for the organic passivation film108, so that patterning can be performed without using a resist.

Thereafter, the contact hole 113 is formed through the organicpassivation film 108 and the inorganic passivation film 107 forestablishing electrical continuity between a pixel electrode 110 formedof ITO and the source electrode 105 of the TFT. An ITO film serving asthe pixel electrode 110 is formed on the organic passivation film 108.

In FIG. 2, an alignment film 111 for aligning liquid crystal moleculesis formed on the pixel electrode 110. A liquid crystal layer 300 isinterposed between the TFT substrate 100 and the counter substrate 200.Initial alignment of liquid crystal molecules of the liquid crystallayer 300 is defined by the alignment film 111 formed on the TFTsubstrate 100 and the alignment film 111 formed on the counter substrate200.

In FIG. 2, color filters 201 are formed on an inner surface of thecounter substrate 200. The color filters 201 of red, green, and blue areformed for each pixel, so that a color image is formed. A black matrix202 is formed between the color filters 201 to improve the contrast ofimage. The black matrix 202 also functions as a light shielding film forthe TFT to prevent photocurrent from flowing into the TFT.

An overcoat film 203 is formed so as to cover the color filters 201 andthe black matrix 202. Since the surfaces of the color filter 201 and theblack matrix 202 have irregularities, the surfaces are flattened withthe overcoat film 203. The counter electrode 204 is formed of an ITOfilm as a transparent conductive film on the overcoat film 203. Voltageis applied between the pixel electrode 110 formed in the pixel of theTFT substrate 100 and the counter electrode 204 formed on the countersubstrate 200 to rotate the liquid crystal molecules, so thattransmitted light or reflected light is controlled to form an image.

A column spacer 205 for defining the gap between the counter substrate200 and the TFT substrate 100 is formed on the counter electrode 204.The column spacer 205 is formed in portions where the black matrix 202is formed, through which the light of a backlight or the like does nottransmit. This is because the alignment of liquid crystal disturbs atthe portion where the column spacer 205 is present, causing light leakfrom the backlight or the like to thereby decrease the contrast.

The height of the column spacer 205 is, for example, 4 μm, which is thesame as the thickness of the liquid crystal layer 300. The column spacer205 is formed of a photosensitive acrylic resin, for example. When anacrylic resin is coated on the entire surface of the counter substrate200 and exposed to light using a mask, only a portion irradiated withthe light becomes insoluble to a developer. Therefore, only the exposedportion is left as the column spacer 205. A resist process is no morerequired by the use of a photosensitive resin, which decreases thenumber of processes.

The alignment film 111 is formed so as to cover the column spacer 205and the counter electrode 204. The initial alignment of the liquidcrystal layer 300 is determined by the alignment film 111 formed on theTFT substrate 100 and the alignment film 111 formed on the countersubstrate 200. This alignment state is changed by rotating the liquidcrystal molecules with the voltage applied between the pixel electrode110 formed on the TFT substrate 100 and the counter substrate 200, sothat light transmitting through the liquid crystal layer 300 iscontrolled to form an image.

As described above, the gap between the TFT substrate 100 and thecounter substrate 200 is defined by the column spacer 205 in a displayregion 10. In the invention, however, the gap between the TFT substrate100 and the counter substrate 200 is defined by using the column spacer205 also in a seal portion. Glass fibers are not mixed into the sealingmaterial 20, and therefore the sealing material 20 includes only anadhesive material.

For making the gap defined by the column spacer 205 precisely the samebetween the display region 10 and the seal portion, the organicpassivation film 108 formed on the TFT substrate 100 is left also in theseal portion at portions on which the column spacer 205 abuts. Forensuring the reliability of adhesion of the sealing material 20, thesealing material 20 is in contact with an inorganic film in the TFTsubstrate 100. It is preferable that the sealing material 20 be indirect contact with the glass substrate also on the counter substrate200 side.

FIGS. 3A to 3C, 5A to 5C, and 7A to 7C show the configurations of theinvention in the vicinity of the seal portion. FIGS. 3A to 3C show theconfiguration of the invention in an A portion in FIG. 1. FIG. 3A is aplan view. In FIG. 3A, the organic passivation films 108 are formed likeislands also at the periphery of the display region 10. However, theorganic passivation film 108 is not formed in the entire seal portion.This is because when the organic passivation film 108 is formed in theentire seal portion, there arises a problem of the adhesive force of thesealing material 20, impairing the reliability of the seal portion.

In FIG. 3A, the column spacers 205 are arranged on the organicpassivation films 108 outside the display region 10. This defines thegap between the TFT substrate 100 and the counter substrate 200.Although omitted in FIG. 3A, the column spacers 205 are formed alsoinside the display region 10. Accordingly, the gap between the TFTsubstrate 100 and the counter substrate 200 is set such that the gap isprecisely the same between inside the display region 10 and outside thedisplay region 10.

FIG. 3B shows the TFT substrate 100 corresponding to a cross sectiontaken along line A-A in FIG. 3A. In FIG. 3B, the gate insulating film102 and the inorganic passivation film 107 are formed in a stackedmanner on the glass substrate. The organic passivation film 108 isformed like an island on the inorganic passivation film 107 at theportions on which the column spacers 205 formed on the counter substrate200 abuts.

In FIG. 3B, the scanning lines are wired on the TFT substrate 100 andcollected to the terminal portion formed on the TFT substrate 100 viathe lead wires. For saving the space for arranging the lead wires, thescanning line lead wires have the two-layer structure of first scanningline lead wires 50 and second scanning line lead wires 60.

FIG. 3C is another cross-sectional view taken along the line A-A of FIG.3A. FIG. 3C shows the state where the counter substrate 200 having thecolumn spacers 205 formed thereon is bonded to the TFT substrate 100 ofFIG. 3B via the sealing material 20. Since the column spacers 205contact the organic passivation films 108 formed on the TFT substrate100, the gap between the TFT substrate 100 and the counter substrate 200can be precisely the same between the display region 10 and the sealportion.

In FIG. 3C, the sealing material 20 is in contact with the inorganicpassivation film 107 on the TFT substrate 100 side. The inorganicpassivation film 107 is formed of an SiN film and has a strong adhesiveforce to an adhesive material, so that the reliability of the sealportion can be improved.

In FIG. 3C, the column spacer 205 and the island-like organicpassivation film 108 corresponding thereto are also formed on thedisplay region 10 side of the portion where the sealing material 20 isformed for precisely defining the gap between the TFT substrate 100 andthe counter substrate 200 in the seal portion.

FIGS. 4A to 4C show a portion corresponding to the A portion of FIG. 1in a conventional example. FIG. 4A is a plan view. In FIG. 4A, not-shownglass fibers are dispersed in the sealing material 20, so that the gapbetween the TFT substrate 100 and the counter substrate 200 is definedby the diameter of the glass fiber. In FIG. 4A, the organic passivationfilm 108 exists to the outside of the display region 10 but does notexist below the sealing material 20.

FIG. 4B is a cross-sectional view of the TFT substrate 100 taken alongline B-B of FIG. 4A. FIG. 4B is similar to FIG. 3B except that theorganic passivation film 108 is not formed in the seal portion. FIG. 4Cis another cross-sectional view taken along the line B-B of FIG. 4A. InFIG. 4C, the not-shown glass fibers are dispersed in the seal portion.

On the other hand, the first scanning line lead wires 50 and the secondscanning line lead wires 60 exist in the seal portion of the TFTsubstrate 100. Therefore, not-shown irregularities are formed on thesurface of the inorganic passivation film 107. When the irregularitiesare pressed by hard glass fibers, there arises a risk that the inorganicpassivation film 107 or the gate insulating film 102, and the firstscanning line lead wires 50 or the second scanning line lead wires 60will be broken.

Contrary to this, in the seal portion of the invention, the columnspacer 205 is an organic material and in contact with the TFT substrate100 via the organic passivation film 108. Therefore, even if a pressureis applied when the TFT substrate 100 and the counter substrate 200 arebonded together, the film such as the inorganic passivation film 107formed on the TFT substrate 100 is not broken. Accordingly, theinvention can precisely define the gap between the TFT substrate 100 andthe counter substrate 200, improve the adhesive force of the sealingmaterial 20 to the TFT substrate 100, and further does not break theinsulating film or conductive film formed on the TFT substrate 100.Therefore, the reliability of the seal portion can be improved.

FIGS. 5A to 5C show a B portion in FIG. 1, that is, a seal portion at anupper left corner portion. FIG. 5A is a plan view. In FIG. 5A, a largecolumn spacer 2051 having a large area is formed at the corner portion.Since an external force is likely to be applied to a corner, the largecolumn spacer 2051 is used. Even the large column spacer 2051 has thesame height as that of the column spacer 205. Further at the cornerportion, the column spacer 205 and the organic passivation film 108corresponding thereto are also formed outside the sealing material 20for moderating the external force applied to the corner portion.

FIG. 5B is a cross-sectional view taken along line A-A of FIG. 5A, onlyillustrating the TFT substrate 100. In FIG. 5B, the scanning line leadwires are formed on the gate insulating film 102 of the TFT substrate100. Since this portion corresponds to the uppermost portion of thedisplay region 10, the scanning line lead wires extend only in thelateral direction.

FIG. 5C is another cross-sectional view taken along the line A-A of FIG.5A. FIG. 5C shows the state where the counter substrate 200 having thecolumn spacer 205 formed thereon is bonded to the TFT substrate 100 inFIG. 5B via the sealing material 20. In FIG. 5C, the sealing material 20is in contact with the inorganic passivation film 107 on the TFTsubstrate 100 side, so that the reliability of the seal portion isimproved, as described with reference to FIGS. 3A to 3C.

FIGS. 6A to 6C show a conventional example in contrast with FIGS. 5A to5C. FIG. 6A is a plan view. In FIG. 6A, the organic passivation film 108exists to the outside of the display region 10 but does not exist in theseal portion. Not-shown glass fibers are dispersed in the sealingmaterial 20 in FIG. 6A, as described with reference to FIGS. 4A to 4C.

FIG. 6B is a cross-sectional view of the TFT substrate 100 taken alongline B-B of FIG. 6A. In FIG. 6B, the organic passivation film 108 doesnot exist at the periphery of the TFT substrate 100. FIG. 6C is anothercross-sectional view taken along the line B-B of FIG. 6A. The columnspacer 205 is formed only in the display region 10 but not formed in theseal portion. The gap between the TFT substrate 100 and the countersubstrate 200 in the seal portion is defined by the glass fibers.

FIGS. 7A to 7C show a C portion in FIG. 1, that is, the seal portion ata lower right corner portion. FIG. 7A is a plan view. In FIG. 7A, thecolumn spacer 205 and the organic passivation film 108 correspondingthereto are formed in the sealing material 20. The column spacer 205 andthe organic passivation film 108 corresponding thereto are formed alsobetween the sealing material 20 and the display region 10.

FIG. 7B is a cross-sectional view taken along line A-A of FIG. 7A, onlyillustrating the TFT substrate 100. In FIG. 7B, the scanning line leadwires are formed on the gate insulating film 102 and the inorganicpassivation film 107 of the TFT substrate 100. FIG. 7C is anothercross-sectional view taken along the line A-A of FIG. 7A. FIG. 7C showsthe state where the counter substrate 200 having the column spacer 205formed thereon is bonded to the TFT substrate 100 in FIG. 7B via thesealing material 20. In FIG. 7C, the sealing material 20 is in contactwith the inorganic passivation film 107 on the TFT substrate 100 side,so that the reliability of the seal portion is improved, as describedwith reference to FIGS. 3A to 3C.

FIGS. 8A to 8C show a conventional example in contrast with FIGS. 7A to7C. FIG. 8A is a plan view. In FIG. 8A, the organic passivation film 108exists to the outside of the display region 10 but does not extend tothe seal portion. Glass fibers are dispersed in the sealing material 20in FIG. 8A, as described with reference to FIGS. 4A to 4C.

FIG. 8B is a cross-sectional view of the TFT substrate 100 taken alongline A-A of FIG. 8A. In FIG. 8B, the organic passivation film 108 doesnot exist at the periphery of the TFT substrate 100. FIG. 8C is anothercross-sectional view taken along the line B-B of FIG. 8A. The columnspacer 205 is formed only in the display region 10 but not formed in theseal portion. The gap between the TFT substrate 100 and the countersubstrate 200 in the seal portion is defined by the glass fibers.

In FIGS. 3A to 3C, 5A to 5C, 7A to 7C, and the like, the sealingmaterial 20 is formed so as to surround the outside column spacer 205.However, the sealing material 20 is not necessarily limited to theconfiguration of surrounding the column spacer 205 on the outermostside. FIG. 9 shows an example where the sealing material 20 is formedbetween the outermost-side column spacer 205 and the column spacer 205present inside the outermost-side column spacer 205. Also in this case,the sealing material 20 is in contact with an SiN film as the inorganicpassivation film 107 on the TFT substrate 100 side, so that thereliability of the seal portion is improved.

FIGS. 10A to 12B show the configurations in which the reliability of theseal portion is further improved. In FIGS. 10A and 10B, a-Si and n+Silayers are formed like islands outside the column spacer 205 in the sealportion, so that a similar effect to that of roughening the top of theinorganic passivation film 107 is provided to improve the adhesiveproperties between the sealing material 20 and the TFT substrate 100.

FIG. 10A is a cross-sectional view of the seal portion. In the sealportion, the column spacer 205 is formed. The column spacer 205 isformed on the black matrix 202 formed like an island. Whether the columnspacer 205 is formed on the black matrix 202, on the black matrix 202and on the overcoat film, or on a stacked fluorescent substance may bedetermined in view of the gap between the TFT substrate 100 and thecounter substrate 200 in the display region 10.

A protrusion 1031 is formed by forming an a-Si layer like an islandoutside the column spacer 205. The island-like a-Si protrusion 1031 isformed on the gate insulating film 102. The inorganic passivation film107 is coated on the island-like a-Si protrusion 1031. As a result, asimilar effect to that of roughening the top of the inorganicpassivation film 107 is provided, and a contact area is increased,whereby the adhesive force of the sealing material 20 is increased toimprove the reliability of the seal portion.

FIG. 10B is a plan view of the seal portion, in which the column spacer205 is formed in the seal portion, and the island-like a-Si protrusions1031 are formed in a line outside the column spacer 205. FIG. 10B showsan example of the arrangement of the island-like a-Si protrusion 1031.The pitch between the island-like a-Si protrusions 1031 may be smalleror greater than that of the example. The arrangement of the island-likea-Si protrusion 1031 is not limited to the in-line arrangement. Theisland-like a-Si protrusion 1031 may be arranged randomly.

In FIGS. 10A and 10B and the like, the protrusion is represented by thea-Si protrusion 1031. However, the n+Si layer formed on the a-Si layermay be simultaneously formed as the island-like protrusion 1031. Theisland-like protrusion can be formed with the a-Si and n+Si layers inthe seal portion at the same time when patterning is performed in thedisplay region 10. The thickness of the a-Si layer is about 150 nm, andthe thickness of the n+Si layer is about 25 nm.

In FIGS. 11A and 11B, a-Si and n+Si layers are formed like islandsinside the column spacer 205 in the seal portion, so that a similareffect to that of roughening the top of the inorganic passivation film107 is provided to improve the adhesive properties between the sealingmaterial 20 and the TFT substrate 100. FIG. 11A is a cross-sectionalview of the seal portion. FIG. 11B is a plan view of the seal portion.

The configuration shown in FIGS. 11A and 11B is similar to that shown inFIGS. 10A and 10B except that the island-like protrusion 1031 formed ofa-Si is formed inside the column spacer 205 in the seal portion. Evenwhen the protrusion 1031 is formed inside the column spacer 205 as shownin FIGS. 11A and 11B, the adhesive force of the sealing material 20 andTFT substrate 100 can be improved, so that the reliability of the sealportion is improved.

In FIGS. 12A and 12B, a-Si and n+Si layers are formed like islands onboth sides of the column spacer 205 in the seal portion, so that asimilar effect to that of roughening the top of the inorganicpassivation film 107 is provided to improve the adhesive propertiesbetween the sealing material 20 and the TFT substrate 100. FIG. 12A is across-sectional view of the seal portion. FIG. 12B is a plan view of theseal portion.

The configuration shown in FIGS. 12A and 12B is similar to that shown inFIGS. 10A and 10B except that the island-like protrusions 1031 formed ofa-Si are formed on both sides of the column spacer 205 in the sealportion. The protrusions 1031 are formed on both sides of the columnspacer 205 as shown in FIGS. 12A and 12B, so that the adhesive force ofthe sealing material 20 and the TFT substrate 100 can be furtherimproved, and the reliability of the seal portion is improved.

FIGS. 13A to 15B show other examples of the configurations in which thereliability of the seal portion is improved. In FIGS. 13A and 13B, acolor filter protrusion 2011 is formed by forming a color filter like anisland outside the column spacer 205 in the seal portion, so that acontact area of the sealing material 20 with the counter substrate 200is increased. Thus, the adhesive force of the sealing material 20 to thecounter substrate 200 is increased to improve the reliability of theseal portion.

FIG. 13A is a plan view of the seal portion. In the seal portion, thecolumn spacers 205 are formed. The protrusions 2011 are formed outsidethe column spacers 205 by forming the color filters like islands. Theisland-like color filter protrusion 2011 may be formed on the blackmatrix 202 or may be directly formed on the glass substrate. Thethickness of the color filter is from 1 μm to 2 μm, and the protrusion2011 formed of the color filter is greater than the protrusion 1031formed of a-Si or the like in the TFT substrate 100. Therefore, a largerroughening effect can be provided.

FIG. 13B is a cross-sectional view of the seal portion, showing anexample where the column spacer 205 is formed on the island-like blackmatrix 202. Although an island-like fluorescent substance is directlyformed on the glass substrate, BM may be arranged as a base depending onthe requirements of the processes or the like.

FIGS. 14A and 14B show an example where the island-like color filters2011 are arranged inside the column spacers 205 in the seal portion.FIG. 14A is a plan view, while FIG. 14B is a cross-sectional view. SinceFIGS. 14A and 14B are similar to FIGS. 13A and 13B except that theisland-like color filters 2011 are formed inside the column spacers 205,the description is omitted.

FIGS. 15A and 15B show an example where the island-like color filters2011 are formed on both sides of the column spacers 205 in the sealportion. FIG. 15A is a plan view, while FIG. 15B is a cross-sectionalview. Since FIGS. 15A and 15B are similar to FIGS. 13A and 13B exceptthat the island-like color filters 2011 are formed on both sides of thecolumn spacers 205, the description is omitted. In the example of FIGS.15A and 15B, since an area for roughening the counter substrate 200 islarge, the adhesive properties between the sealing material 20 and thecounter substrate 200 can be further improved.

Embodiment 2

In Embodiment 1, the TN type liquid crystal display device, which ismost typical, has been described. However, the invention is not limitedto the TN type liquid crystal display device but can be applied to othertypes. An IPS (In Plane Switching) type liquid crystal display devicecontrols light by rotating liquid crystal molecules 301 in thehorizontal direction with a lateral electric field and has excellentviewing angle characteristics.

FIG. 16 is a cross-sectional view of the display region 10 of an IPStype liquid crystal display device. Only different portions from theconfiguration of the typical liquid crystal display device describedwith reference to FIG. 2 will be described. In FIG. 16, a TFT is formedon the TFT substrate 100, and the organic passivation film 108 is formedon the inorganic passivation film 107, similarly to FIG. 2. An n+Silayer is formed on the semiconductor layer 103, but the n+Si layer isomitted in FIG. 16.

In FIG. 16, the counter electrode 204 is formed of ITO in a planar shapeon the organic passivation film 108. An inter-layer insulating film 120is formed on the counter electrode 204. The pixel electrode 110 having acomb-teeth shape is formed on the inter-layer insulating film 120. Whenvoltage due to a video signal is applied to the comb-teeth electrode,and a reference voltage is applied to the counter electrode 204, linesof electric force indicated by arrows in FIG. 16 are generated to rotatethe liquid crystal molecules 301, thereby controlling the amount oflight transmitting through the liquid crystal layer 300. The alignmentfilm 111 is formed on the pixel electrode 110.

In FIG. 16, the black matrix 202, the color filters 201, and theovercoat film 203 are formed on the counter substrate 200 similarly toFIG. 2. In FIG. 16, the alignment film 111 is formed on the overcoatfilm 203. The counter electrode 204 is not formed on the countersubstrate 200. This is because the counter electrode 204 is formed onthe TFT substrate 100 in the IPS type liquid crystal display device.

In the IPS type liquid crystal display device, since the counterelectrode 204 is not formed on the counter substrate 200, noise from theoutside enters from the counter substrate 200 side. For preventing this,a surface conductive film 210 is formed to shield the inside of the IPStype liquid crystal display device.

FIGS. 17A to 17C, 19A to 19C, and 21A to 21C are enlarged views of theseal portions corresponding to the regions A, B, and C in FIG. 1 in theseal portion when the invention is applied to the IPS type liquidcrystal display device.

FIGS. 17A to 17C are enlarged views of the region A in FIG. 1. FIG. 17Ais a plan view. FIG. 17A is similar to FIG. 3A, but the inter-layerinsulating film 120, which is not shown, is formed on the organicpassivation film 108. FIG. 17B is a cross-sectional view of the TFTsubstrate 100 portion taken along line A-A of FIG. 17A. In FIG. 17B, theinter-layer insulating film 120 is formed on the organic passivationfilm 108 and the inorganic passivation film 107.

Since the inter-layer insulating film 120 is formed of an SiN film as aninorganic film, the inter-layer insulating film 120 has excellentadhesive properties to the sealing material 20. Accordingly, thereliability of the seal portion can be further improved compared withthe typical TN type liquid crystal display device described withreference to FIGS. 3A to 3C and the like.

FIG. 17C is another cross-sectional view taken along the line A-A ofFIG. 17A. As shown in FIG. 17C, the column spacers 205 are in contactwith the inter-layer insulating film 120 formed on the organicpassivation film 108. Since the sealing material 20 is in contact withthe inter-layer insulating film 120 as an inorganic film and is notcontact with the organic passivation film 108 on the TFT substrate 100side, the reliability of the seal portion is extremely high.

FIGS. 18A to 18C show a conventional example for the same portion as inFIGS. 17A to 17C for comparison. FIG. 18A is a plan view. FIG. 18B is across-sectional view taken along line B-B of FIG. 18A, showing only theportion of the TFT substrate 100. FIG. 18C is another cross-sectionalview taken along the line A-A of FIG. 18A. Since FIGS. 18A to 18C aresimilar to FIGS. 4A to 4C except that the inter-layer insulating film120 is formed on the organic passivation film 108 and the inorganicpassivation film 107, the description is omitted.

FIGS. 19A to 19C are enlarged views of the region B in FIG. 1. FIG. 19Ais a plan view. FIG. 19A is similar to FIG. 5A, but the inter-layerinsulating film 120, which is not shown, is formed on the organicpassivation film 108. FIG. 19B is a cross-sectional view of the TFTsubstrate 100 portion taken along line A-A of FIG. 19A. FIG. 19C isanother cross-sectional view taken along the line A-A of FIG. 19A. SinceFIGS. 19B, 19C, and the like are similar to FIGS. 5A to 5C except thatthe inter-layer insulating film 120 is formed on the organic passivationfilm 108 and the inorganic passivation film 107, the description isomitted.

FIGS. 20A to 20C show a conventional example for the same portion as inFIGS. 19A to 19C for comparison. FIG. 20A is a plan view. FIG. 20B is across-sectional view taken along line B-B of FIG. 20A, showing only theportion of the TFT substrate 100. FIG. 20C is another cross-sectionalview taken along the line B-B of FIG. 20A. Since FIGS. 20A to 20C aresimilar to FIGS. 6A to 6C except that the inter-layer insulating film120 is formed on the organic passivation film 108 and the inorganicpassivation film 107, the description is omitted.

FIGS. 21A to 21C are enlarged views of the region C in FIG. 1. FIG. 21Ais a plan view. FIG. 21A is similar to FIG. 7A, but the inter-layerinsulating film 120, which is not shown, is formed on the organicpassivation film 108. FIG. 21B is a cross-sectional view of the TFTsubstrate 100 portion taken along line A-A of FIG. 21A. FIG. 21C isanother cross-sectional view taken along the line A-A of FIG. 21A. SinceFIG. 21B, 21C, and the like are similar to FIGS. 7A to 7C except thatthe inter-layer insulating film 120 is formed on the organic passivationfilm 108 and the inorganic passivation film 107, the description isomitted.

FIGS. 22A to 22C show a conventional example for the same portion as inFIGS. 21A to 21C for comparison. FIG. 22A is a plan view. FIG. 22B is across-sectional view taken along line B-B of FIG. 22A, showing only theportion of the TFT substrate 100. FIG. 22C is another cross-sectionalview taken along the line B-B of FIG. 22A. Since FIGS. 22A to 22C aresimilar to FIGS. 8A to 8C except that the inter-layer insulating film120 is formed on the organic passivation film 108 and the inorganicpassivation film 107, the description is omitted.

In FIGS. 17A to 17C, 19A to 19C, 21A to 21C, and the like, the sealingmaterial 20 is formed so as to surround the outside column spacers 205.However, the sealing material 20 is not necessarily limited to theconfiguration of surrounding the column spacer 205 on the outermostside. FIG. 23 shows an example where the sealing material 20 is formedbetween the outermost-side column spacer 205 and the column spacer 205present inside the outermost-side column spacer 205. Also in this case,the sealing material 20 is in contact with an SiN film as theinter-layer insulating film 120 on the TFT substrate 100 side, so thatthe reliability of the seal portion is improved.

Embodiment 3

Embodiments 1 and 2 show the examples where the organic passivation film108 is formed on the inorganic passivation film 107. Some liquid crystaldisplay devices use only the inorganic passivation film 107 as aprotective film for a TFT without using the organic passivation film108. The invention can also be applied to such a case.

FIG. 24 is a schematic cross-sectional view of the seal portion inEmbodiment 3. In FIG. 24, the column spacer 205 is formed in the sealportion, so that the column spacer 205 defines the gap between the TFTsubstrate 100 and the counter substrate 200 in the seal portion.Accordingly, the same gap as that in the display region 10 can bemaintained.

In FIG. 24, glass fibers are not dispersed in the sealing material 20.Therefore, even when the two-layer wiring of the first scanning linelead wires 50 and the second scanning line lead wires 60 is formed inthe seal portion, the inorganic passivation film 107, the gateinsulating film 102, the scanning line lead wires, or the like is notbroken. That is, when the scanning line lead wires have the two-layerstructure, the irregularities on the surface of the inorganicpassivation film becomes large. However, when the gap in the sealportion is set not with hard glass fibers but with column spacers formedof a resin like the invention, the breakage of the scanning line leadwires or the like can be prevented.

The sealing material 20 is in contact with the inorganic passivationfilm 107 formed of SiN on the TFT substrate 100 side. Therefore, theadhesive force is high, and the reliability of the seal portion is high.The alignment film does not exist in the seal portion both on the TFTsubstrate 100 side and on the counter electrode 204 side. Further, FIG.24 has a feature in that the column spacer 205 is also formed outsidethe sealing material 20. With this configuration, the gap between theTFT substrate 100 and the counter substrate 200 can be precisely set inthe seal portion.

FIG. 25 is similar to FIG. 24 in that the column spacers 205 are formedin the sealing material 20. However, the column spacers 205 are alsoformed inside the sealing material 20. Also with the configuration ofFIG. 25, the gap between the TFT substrate 100 and the counter substrate200 can be precisely set in the seal portion.

FIG. 26 is similar to FIG. 24 in that the column spacer 205 is formed inthe sealing material 20. However, the column spacers 205 are formed onboth sides of the sealing material 20. Since the column spacers 205 areformed on both sides of the sealing material 20 in the configuration ofFIG. 26, the gap between the TFT substrate 100 and the counter substrate200 can be set more precisely in the seal portion. Although FIGS. 24 to26 show the typical TN type liquid crystal display device, theconfiguration of Embodiment 3 can be applied to the IPS type liquidcrystal display device in the same manner.

In the above description, the invention is applied to the configurationof the typical TN type in Embodiment 1 and to the configuration of theIPS type in Embodiment 2. However, the invention is not limited to theseliquid crystal display devices but can be applied to a so-called VA(Vertical Alignment) type liquid crystal display device or the like.

1. A liquid crystal display device comprising: a TFT substrate havingpixels each including a pixel electrode and a TFT formed in a matrix toform a display region; a counter substrate having color filters formedcorresponding to the pixels and facing the TFT substrate via a sealportion having sealing material formed at the peripheries of thesubstrates; and liquid crystal interposed between the TFT substrate andthe counter substrate, wherein the TFT is covered with at least one ofan inorganic passivation film, an organic passivation film, and aninter-layer insulating film, the gap between the TFT substrate and thecounter substrate is defined in the seal portion by first column spacersformed on the counter substrate and at least one of a first island-likeorganic passivation film, and the inter-layer insulating film formed onthe TFT substrate, and in the seal portion, the sealing material coversthe first column spacers and the first island-like organic passivationfilm and is in contact with at least one of the inorganic passivationfilm and the inter-layer insulating film on the TFT substrate side. 2.The liquid crystal display device according to claim 1, wherein secondcolumn spacers are formed on the counter substrate side outside of theseal portion where the sealing material is formed, and a secondisland-like organic passivation film is formed so as to face the secondcolumn spacers on the TFT substrate side.
 3. The liquid crystal displaydevice according to claim 1, wherein second column spacers are formed onthe counter substrate side on the display region side of the sealportion where the sealing material is formed, and a second island-likeorganic passivation film is formed so as to face the second columnspacers on the TFT substrate side.
 4. The liquid crystal display deviceaccording to claim 1, wherein in the seal portion, semiconductor filmsare formed like islands on the TFT substrate side.
 5. The liquid crystaldisplay device according to claim 1, wherein in the seal portion, thecolor filters are formed like islands on the counter substrate side. 6.The liquid crystal display device according to claim 2, wherein thesecond column spacers are formed on the counter substrate side on thedisplay region side of the seal portion where the sealing material isformed, and the second island-like organic passivation film is formed soas to face the second column spacers on the TFT substrate side.
 7. Theliquid crystal display device according to claim 2, wherein in the sealportion, semiconductor films are formed like islands on the TFTsubstrate side.
 8. The liquid crystal display device according to claim2, wherein in the seal portion, the color filters are formed likeislands on the counter substrate side.
 9. The liquid crystal displaydevice according to claim 6, wherein in the seal portion, semiconductorfilms are formed like islands on the TFT substrate side.
 10. The liquidcrystal display device according to claim 6, wherein in the sealportion, the color filters are formed like islands on the countersubstrate side.
 11. The liquid crystal display device according to claim9, wherein in the seal portion, the color filters are formed likeislands on the counter substrate side.
 12. The liquid crystal displaydevice according to claim 1, wherein the TFT is covered with theinorganic passivation film and the organic passivation film, and in theseal portion, the sealing material is in contact with the inorganicpassivation film on the TFT substrate side.
 13. The liquid crystaldisplay device according to claim 1, wherein the TFT is covered with theinorganic passivation film and the organic passivation film, the counterelectrode is formed on the organic passivation film, the inter-layerinsulating film is formed on the counter electrode, the pixel electrodeis formed on the inter-layer insulating film, and in the seal portion,the sealing material is in contact with the inter-layer insulating filmon the TFT substrate side.
 14. The liquid crystal display deviceaccording to claim 1, wherein the TFT substrate is covered with theinorganic passivation film, in the seal portion, first scanning linelead wires and second scanning line lead wires are formed in differentlayers on the TFT substrate, and in the seal portion, the sealingmaterial is in contact with the inter-layer insulating film on the TFTsubstrate side.
 15. The liquid crystal display device according to claim1, wherein the TFT substrate is covered with the inorganic passivationfilm, the inter-layer film is formed on the counter electrode, the pixelelectrode is formed on the inter-layer insulating film, and in the sealportion, the first scanning lead wire and second scanning lead wire areformed in different layers on the TFT substrate.